Telephone system



Dec; 2, 1930. w. SCHULZ ET AL TELEPHONE SYSTEM Ofiginal Filed 001:. 9, 1926 3 Sheets-Sheet 1 Ifiusn ar's Meruer ECZ'MIZI-JNHX FT'iSChkE 'KEII SchTFFmann Dec. 2, 1930. w. SCHULZ ET AL 1,783,312

TELEPHONE SYSTEM Original Filed Oct. 9, 192.6 SSheetS-Sheet 2 I van urs InIeruez" SEZYUZZP-JFIHX FFISEhkE KEFZ- Efffiffmann Dec. 2, 1930. w. SCHULZ ET AL 1,783,312 I TELEPHONE SYSTEM 7 Original Filed Oct. 9, 1926 s Sheets-Sheet 3 f ij MEPHEI" Schulz ""NHX FFE' kE KBPZ Schfimann to the exchange A. i V

' The .drawings, comprising Figs '1- 3, in

Patented Dec. 2, 1930 UNI'TED STATES-PATENT OFFICE WERNER SCI-IULZ, Max FRISCHKE, nn KARL soninrmann, or BERLIN, GERMANY, ASSIGNOBS TO SIEMENS & HALSKE AKTIENGESELLSCHAFT, or wnnnnnwnnx,

SIEMENSSTADT, NEAR BERLIN GERMANY 'rnnnrnoun SYSTEM Application filed October 9, 1926, Serial No. 14o,44.s, and in Germany October 22, 1925. Renewed May because they have to be protected frominduced currents (railway currents, eta).

According to the invention, the automatic transmission of signals can be achieved for example in that when the plug is inserted into the jack of the trunk lineat the telephone exchange Abforpthe purposeoi initiatinga call, an alternating current is sent'from the exchange A to the exchange B and, on being received, thereat, special kn'ogwn switching meanscause the calling lamp to light. When at the exchange A the plug is withdrawn from the jack of the trunk line, forexample atthe end of the conversation, a further current impulse goes to the exchange B- andvextinguishes the supervisory lampthereat, For

transmitting signals from the subscriberto theexchang'e A, alternating currents are sent from'the exchange B to, the exchangeA forv operating the supervisoryv lampat the exchange A, the condition thereof depending. on whether the receiver is lifted; or replacedat' the subscribers instrument. Alternately the problem of automatically sending signals directover trunk lines, whichiare isolated by repeaters, can be solved by-si-gnalling from the exchange A to the exchange B in the.

manner described above, and by signalling from the exchange B-to the .exchange'A by transmitting the particular maintained cone dition with the assistanceof an alternating current of a frequency different :Erom'that used for the alternating currentfromithe exchange A to the exchange B.. Another solution of this problem consists in transmitting a direct current impulse from the exchange A to the exchange B and analternating current impulse trom the exchange example audible frequency.

Figure 3 shows a circuit arrangement, in which the signalling from the telephoneexchange 1 to B is effected by direct current impulses, and from B to A by. maintained alternating current. I

A detailed description of the invention may now be given. Referring to Figure-1, when the operator at the position KA plugs into the unction 'line,the supervisory lamp in the cord (not shown) is lighted and the relay C is energized by its winding I over the contact lcll'and the c-leadover the plug:

1. Earth over the pluginserted in the jack Kc, back contact 7011, winding I of relay C, battery, earth. i r V The relay C with its contactclQ. operates the relay J 1 2. Earth, back contact 70011, front contact 012, relay J, battery, earth; i

The relay J is operated; at its contact 7'1 it disconnects the relayR, and over the front contacts 7'2 and y3 and the repeater U1 it sends ringing current to theline. -Furthermoreit energizesthe relay K0 and the wind ing II ofthe'relay C overthe back contacts I lc12and7c13: i

3. Earth, winding not relay C, back contact Z013. frontcontact 74, back contact Z012,

new locksitself in series with relay K1: 1

4. Earth, relay K1, double front contact 70012, relay KO, battery, earth.

After relay K1 has operated, the relay C locks itself over its winding I and its contact 013. At the position KB the relay R2 re sponds to the ringing current impulse sent out by the relay J at the position KA, and the relay R2 at its front contact 921 operates the relay U2:

5. Earth, back contact n31, front contact 1 21, back contact @0552, relay U2, battery, earth.

When the relay R2 has been ole-energized, (at the end of the ringing impulse sent by relay J at the position KA) the relay U2 locks itself over its contact H21 in series with relay U3, which is operated:

6. Earth, relay U3, double front contact 1421, relay U2, battery, earth.

Relay U2 also closes the circuit of the supervisory lamp UL:

7. Earth, back contact 791, front contact L622, lamp UL, battery, earth.

The operator at the exchange B plugs into the wanted connection, thereby energizing the relay P, so that the supervisory lamp is again extinguished by the opening of the contact 791. When the wanted subscriber answers, the relays S1 and S2 are energized and the relay S0 is energized by its winding I over the back contact 7031:

8. Earth, front contacts $11, 821, back contact k31, winding I of relay SO, battery, earth.

The relay closes a circuit for the relay J 2 over:

9. Earth, front contact n23, back contact 7021, front contact 801, relay J2, battery, earth. I

Relay J2 is operated. At contact 721 it disconnects the calling line R2 from the relay and over the contacts j22, 7'23 it sends ringing current over the repeater U2 to the line. Furthermore, at contact j24the winding II of the relay S0 is energized:

10. Earth, winding II of relay SO, back contact 7032, front contact 724, contact 7035., relay 702, battery, earth.

The relay J2 is now disconnected at the contact 7021, and at contact 722 and I23 it in terrupts the transmission of ringing current. At the contact 721 the relay R2 is again con nected to the line and'the relay K3 is operated in series with the relay K2:

11. Earth, relay K3, double front contact 7022, relay K2, battery, earth.

The winding I of relay SO new locks the relay over its front contact 802 as follows:

12. Earth, front contact 811, .921 and 502, winding I of relay SO, battery, earth.

At the exchange A the relay B is operated by the impulse of ringing current sent from the exchange B, and the relay R connects up the relays U0 and U1 at the exchange A in the same manner as the relay R2 at the exchange B. Thereupon the relay UO at its contact @601 applies earth to the a lead and so in known manner extinguishes the supervisory lamp in the cord circuit of the operator. At the end of the conversation when the subscriber hangs up his receiver, current is removed from the relays S1 and S2, and the relay SO in circuit 12 is also de energized. The relay K2 being now energized, the relay J2 is operated over the back contact of 803:

13. Earth, front contacts 1,123 and 7023, back contact 503, relay J 2, battery, earth.

The relay R2 is again disconnected from the line and ringing current goes to the line over the repeater U2. The operation of the relay J2 also short circuits the relay K2, which therefore falls back:

14. Earth, battery, resistance SW3, front contacts 7033 and 324, double front contact 7022, relay K2, battery, earth.

During the impulse transmission the relay K8 holds itself over its own contacts and the contact j24c.

Upon falling back, the relay K2 at its contact 7023 opens the circuit of the relay J2, which then falls back. The transmission of ringing current is ended and the relay R2 is again connected to the line.

After the release of the relay J2, the relay K3 is also released, which during impulse transmission locked itself over its own circuit:

1 1a. Earth, battery, resistance SE 3, front contacts 7033, i2 1 and 7034, relay K3, earth.

The back contact 7031 of the relay K3 shunts the front contact 802, hence the relay S0 is again operated if in the meantime the subscriber has again taken down his receiver, and another impuse of ringing current can be sent to the exchan e A. The impulse sent from the exchange B after the receiver has been hung up at the subscribers instrument operates the relay It at the exchange A. The latter short circuits the relay UO. (See the short circniting of K2 circuit 1.4). Relay Ur) falls back and at its contact n01 it removes earth from the a lead, thus in known manner causing the lighting of the supervisory lamp in the operators cord circuit. The relay U1 during the current impulse locks itself over:

15. Earth, front contact 014, relay U1, front contacts U12, 1" and M13, resistance ST], battery, earth; and it only falls back after the impulse has ended (therefore after the release of the relay It). r

The disconnect signal having been received, the operator at the exchange A withdraws the plug from the jack K'v, thereby causing the release of the relay C. As the re lay K0 is energized (circuit a), the relay J is operated over the back contact 011 and the front contact 70011. The relay fl sends ringing current to the exchange B in exactly the same manner as previously when the junction line was seized, the relay R being disconiiu nected. After relay J has operated, therelay KO falls back slowly (owing to the short circuit) (see relay K2 in circuit 1%) and at contact 7c011 it opens the circuit 2 of the relay J. Upon the release of the relay J, ringing current is disconnected from the line, and the relay K1 is die-energized; during the impulse transmission it locked itself over its own contact and contact 1'4, (see relay K3 in circuit lea). Thus the winding l of the relay Gris again connected to the jack K and it is again ready to initiate a fresh seizing impulse. The impulsetransrnitted: by the withdrawal of the plug at the exchange A is received at theexchangeB by the'relay R2, which de-energizes the relay U2 by short circuiting it. The relay U2 was energized in series with the relay U1 (circuit 6) 16. Earth, battery", resistance S y V2, front contacts M33, 121, double front contact @421 relay U2, battery, earth." r

The supervisory lamp} UL is lighted over the following circuit r 17. Earth, front contact 392, back contact 7124, lamp UL, battery,earth. The circuit 13 of the impulse relay J2 is opened at the contact @023. y i

At the end of the impulse (relay R2 released)- the relay U3 falls back. The relays U2 andU3 are ready to receive another seizing impulse?The-operator at the exchange B releases the connection byi ithdrawing the plug BS, whereupon the relay P falls back and extinguishes the lamp UL (circuit 17) Referring nowto Figure 2, which showsa second method for carrying "cut-the object of the invention, when the operator at the exchange A plugs into the ack K221 of the unction line, the supervisory lamp in her cord circuit is lighted in known manner and 'the'relay 1131s operated:

- 18. Earth, over the plug and the jack K111, back contact'c21, relay R3, battery, earh.

Rmgmgeurrent of perlods is then sent to the exchange B. Furthermore the relay' C2 is energized over the contact 1731:

19. Earth, front contact r31,frelay,'G2, winding 1, battery, earth.

The relay C2 by opening its contact 021,

disconnects the relay R8 from the jack K01 and locks itself over the front contact: 022:

20. Earth overthe plug and jack Kel H of relay front contact 022, winding battery, earth. V r r The transmission of ringing current to the line is ended after the releasecfthe relay R3. The relay R4 at the exchange B was energized by the incoming ringing current. At its contact r41 it-cleses a circuit for the relay U4: 7.

121. Eartlnback contact 2651, front contact earth-.1 i

. The relay closesthe circuitfof the'supernot respond toalternating current of 500.

cycles). The relay U5 is now operated'and locks itself in series with U4: i

23. Earth, relay U5, double frontcontact relay UA, battery, earth. 7

The alternating current arriving at the exchange A operates the relay T, thereby energizing the relay V over the contact 23.. The latter disconnects the line in order to prevent alternating current reaching the opera tor, and at the same time lights the supertisery lamp inthe cord 0' edit by removing earth from the a lead.

lVhen the operator at the exchange 13 lugs into the wanted line, the relay P2 is perated which, by opening the contact 1921,

nguishes the lampl H12. When the wanted subscriber answers,- the relay S3 "is energized and. at itscontacts s31,

532 it disconnects the alternating current from the line. At its'contact 833, $34 the wanted subscribers line is connected up. If alternating current fails, the relay T at the exchange A falls back and so also. releases he relay V, which here likewise switches through thejconnection. At the same time supervlsory lamp 1n the operators cord flan circuit at the exchange A is extinguished.

At the end of the conversation, when the subscriber hangs up the receiver, the relay SZilS LlGQDGFg'iZBd. The relay T at the exchange A is operated by the alternating current coming fronrthe exchange B and it in turn operates the relay-V, whichatits contacts o1,' v2, d sconnects the l ne'and sends the clearing signal to the operator at the exchange A over the contact '03. 'If' the operator at the exchange A now releases the.

connection by. withdrawing [the plug, the relay C2 falls back and the relay R3 is operated ove'r the frent contact a l of the. relay V, which is still maintained energized:

023, relay R3, battery, earth.

'Atits front'contacts r32, r83, the relay sends ringing current .to the exchange B. Furthermore the relay C2 is once more operated, owing to the operatienofthe relay R3 25. Earth, front contact r31, winding I of relay C2, battery, earth. 7

At its contact 023 the relay opens the circuit of t is relay RS. Relay R3 falls back and cannot again be operated, because the relay inging current arriving in the exchang'eB 24. Earth, front contact 024, back contact V; has also fallen back in the meantime. The

energizes the relay R4, which short circuits the relay U4:

26. Earth, battery, resistance SlV4, front contact 1153, and 141, double front contact 2445, relay U4, battery, earth.

On falling back relay U4 disconnects at the contacts @443 and n44 alternating current from the line. The lamp UL2 is lighted:

27. Earth, front contact p22, back contact M46, lamp UL2, relay K4, battery, earth.

The relay U5 remains energized in the following circuit:

28. Earth, relay U5, front contacts M54, 1 41 and @453, resistance SW 4, battery, earth.

At the end of the ringing impulse the relay R4 falls back and by opening the contact r41 it disconnects the relay U5. The operator at the position B releases the connection by withdrawing the plug BS2, whereupon the relay P2 falls back and extinguishes the lamp U L2 by opening the contact 3922.

Referring now to Figure 3, which shows the third method for accomplishing the object of the invention, when the operator at the exchange A inserts the plug into the jack Ko2 of the junction line, the relay R5 is operated:

29. Earth over the plug and jack K412, back contact 031, relay R5, battery, earth.

It closes its contacts 151 and 1 52, thereby applying over the choke coils D1 1 and D1 2 an unearthed voltage of volts to the windings of the repeater U4 connected to the a and 5 leads going to the exchange B; hence the relay R6 is energized:

30. Positive pole of the battery, choke coil D1 2, front contact r52, repeater U4 winding I, b-lead, repeate 5 winding 1, relay R6, repeater U5 winding II, a-lead, repeater U4 winding 11, front contact 151, choke coil D7 1, negative pole of the battery.

Furthermore the relay G3 was energized as follows:

31. Earth, front contact 153, winding I of relay C3, battery, earth.

It opens the circuit 27 at contact (231, and closes a locking circuit for itself at contact 032:

32. Earth over the plug and jack K112, front contact 032, winding H of relay C3, battery, earth.

The relay R5 falls back and opens its con tacts 7 51 and 152. The voltage is thereby rein-ow-xd from the line and the windings I and c repeater U4 connec ed together over the back contacts r54, r55. The relay R6 at the exchange B has been operated by the direct current voltage applied at the exchange A and has operated the relay U6 33. Earth, back contact 1171, front contact 461, back contact 1072, relay U6, battery, earth.

Relay U6 is likewise operated and closes the following circuit for the supervisory lamp ll of th 34. Earth, back contact 1031, front contact u61, lamp U113, relay K5, battery, earth.

The lamp UL3 is lighted. Furthermore ringing current is sent to the exchange A over the front contacts 1162, M63 and the windings III and IV of the repeater U5 35. Source of ringing current, front contact 1162, back contact 851, windings Ill and IV of repeater U5, back contact 852, front cantact 1463, source of ringing current.

Voltage having been removed at the exchange 4 (by relay R5), the relay R6 falls back. (Relay R6 does not respond to ringing current). Hence relay U7 is operated and locks itself in series with relay U6 36. Earth, relay U7, double front contact u64, relay U6, battery, earth.

The ringing current arriving in the exchange A operates the relay T2, which energizes the relay V2:

37. Earth, front contact $21, relay V2, battery, earth.

This at the contacts 1221, 4122, disconnects the line in order to prevent ringing current reaching the operator, and at the same time lights the supervisory lamp in the cord circuit at the exchange A over the front contact 023.

lVhen the operator at the exchange B plugs into the wanted line, the relay P3 is operated, which extinguishes the lamp UL3 by opening the contact 7731. l/Vhen the wanted subscriber answers, the relay S5 is operated. At its contacts 851 and 352 it disconnects the ringing current from the line and at the contacts 853, 354 it switches through the wanted subscribers line. If ringing current fails at the exchange A the relay'T2 falls back and opens the circuit 37. Hence the relay V2 also falls back. The junction line is switched through at the contacts 4221, 4122, and at the same time the supervisory lamp is extinguished in the cord circuit of the Operator at the exchange A.

At the end of the conversation, when the subscriber hangs up the receiver again, the relay S5 is de-energized; the relay T2 at the exchange A is operated by the ringing current arriving from the exchange B and it again energizes the relay V2, which severs the line in known manner and sends the clearing signal to the operator at the exchange A. When the operator at the exchange A" severs the connect-ion by withdrawing the plug, the relay C3 falls back. Relay R5 is operated over the front contact 4224 of the still energized relay V2:

38. Earth, front contact 1124, back contact 033, relay R5, battery, earth.

Relay B5 again applies voltage to the line at the exchange B (circuit 30). Furthermore the relay C3 is again energized at the contact 153 (circuit 31) and at 033 it opens the circuit 36. The relay R5 falls back and cannot be again operated, because the relay V2 has also fallen back in the meantime.

, U7 as already described." The operator at the exchange B releases the connection by withdrawing the plug BS3, thereby causing the relay P to fall back, which at contact 7932 opens the circuit of lamp UL3 to extinguis'h it.

What is claimed is:

v1. In a telephone system, a first and a second exchange, a trunk comprising inductively coupled sections extending between said exchanges, means at said first exchange for establishing a connection over said trunk, means responsive to said establishment for producing a momentary current flow of a certain character over said trunk, means at said second exchange responsive to said momentary current flow for operating a signal thereat and for producing a current flow of a difierent character over said trunk line to actuate a signal at said first exchange.

2. In a telephone system, a first and a second exchange, a trunk comprising inductively coupled sections extending between said exchanges, means at said first exchange for establishing a connection over said trunk, means responsive to said establishment for producing a momentary current flow of a certain character over said trunk, means. at said second exchange responsive to said momentary current flow for operating a signal thereat and for producing a current flow of a difierent character over said trunk line to actuate a signal at said first exchange, means for extending said connection to a called party, and means operative when said called party responds for interrupting said current flow of a different character to de-actuate said signal at said first exchange.

3. In a telephone system, a trunk comprising incoming and outgoing sections, means responsive to the extension of a connection over one of said sections for sending a momentary impulse of current to the other section, means responsive to the extension of a connection over the other section for continuously transmitting current impulses to the first section, and signalling means. at each section responsive to impulses transmitted from the other section. v V

4. In a telephone system, a trunk comprising incoming and outgoing inductively coupled sections, means for momentarily trans.- mitting current of like characteristics from one section to the other responsive to the establishment and to the breaking downof a connection over said one section, means for continuously transmitting current impulses of like characteristics from said other sect on to said first sect on responsive to the establishment and to the breaking down of a connection over said second section, and sig- ;nalling means at each section operative responsive to the current transmitted from the othersection. I a V 5. In a telephone system comprising a trunk extending between two'exchanges, a source of characteristic current at the first exchange, means responsive to the establishment or a connection with the trunk for momentarily connecting said current source to the trunk over a fixed current path, means responsive to the disestablishment of the connection with the trunk for momentarily reconnecting said current source to the trunk overthe same circuit path previously'used, and a signal at the second exchange operated responsive to each of said'momentary connections.

6. In a telephone system comprising a trunk extending between two exchanges, a source of characteristic current at the first exchange, means for momentarily connecting said current source to the trunk responsive initially to the establishment of a connection with the trunk and subsequently to the-disestablishment'of the connection there from,fa signal at the second exchange, and a single relay bridged across the trunk'at the second exchange, said relay operating responsive to each of said momentary connections of the current source to actuate said signal.

7 Ina telephone system comprising a trunk extending between two exchanges,

means for extending a call from the first exchange to the second exchange via the trunk, means at the second exchange for further extending the call, means for answering the call, a source of characteristic current at each exchange, a 'supervisory' circuit at the first exchange, a signal at the second exchange, means in the first exchange responsive to the establishment of a connection with the trunk for momentarily connecting the current source at the first exchange to the trunk over a fixed circuit means responsive to current from said source for actuating'said signal, means responsive to the further extension of the call for deactuating said signal, means responsive to the answering of the call for connecting the current source at the second exchange to the trunk, means responsive to current from last said source for rendering said supervisory circuit efiective, and means responsive to the disestablishmentjof the connection from the trunk at the first exchange for momentarily reconnecting first said current source to thetrunk to reactuate said'signal.

[ill

8. In a telephone system comprising a trunk extending between two exchanges, a source of characteristic current at the first exchange, means responsive to the establishment of a connection with the trunk for momentarily connecting said current source to the trunk over a fixed circuit, means responsive to the disestablishment of the connection from the trunk for reconnecting said current source to the trunk over the same circuit previously used, a signal at the second exchange, and a single relay bridged across the trunk at the second exchange, said relay operating responsive to each of said momentary connections of the current source to actuate said signal.

9. In a telephone system, a trunk comprising a plurality of inductively connected sections extending between two exchanges, means for extending a call from the first exchange to the second exchange via said trunk, means for answering the call, a source of alternating current in the second exchange, means responsive to the answering of the call for connecting said current source to the trunk, and means in the first exchange responsive to said alternating current for connecting a characteristic potential to a talking conductor of one section of said trunk.

10. The combination with a trunk comprising two talking conductors and a sleeve conductor terminating in a manual jack, of a relay normally connected to the sleeve conduct-or and operated responsive to the extension of a call to the trunk via the ack, a second relay controlled by the first relay, and means controlled by the second relay for connecting itself to the sleeve conductor in place of the first relay.

11. The combination with a trunk comprising two talking conductors and a sleeve conductor, of a ringing relay normally con nected to the sleeve conductor and operated responsive to the extension of a call to the trunk, a holding relay energized initially re sponsive to the operation of the ringing relay, and means controlled by the holding relay when energized for locking itself to the sleeve conductor and for disconnecting the ringing relay therefrom.

12. In a telephone system, a trunk terminating in a manual jack, a relay normally connected to the sleeve of said jack, a second relay, means for operating said first relay when the trunk is connected with by way of said jack, means responsive to the operation of said first relay for applying ringing current to the trunk and for operating said second relay, and means responsive to the operation of said second relay for disconnecting said first relay from the sleeve of the ack and for connecting the second relay thereto.

13. In a telephone system, a trunk terminating in a manual jack, a relay normally connected to the sleeve of the jack, a second WERNER SCHULZ. In witness whereof, I hereunto subscribe my name this 21st day of September, A. D.

MAX FRISCHKE.

In witness whereof, I hereunto subscribe Q my name this 21st day of September, A. I).

KARL SCHIFFMANN. 

